Bacterial Diversity in Rumen Fluid of Dairy Cattle in Washington

Nicola Beatty, Animal Vet Science
Third Place: Undergraduate Presentations

Abstract: The rumen serves as a large fermentation vat that plays host to a variety of microbial populations required for effective digestion and breakdown of carbohydrates and proteins for energy utilization in dairy cattle. Of these microbes, the most prevalent genera are Ruminococcus, Fibrobacter, Butyrivibrio, and Prevotella due to their ability to digest cellulose and hemicellulose1. Although these major genera are well studied, there are additional existing microbial populations in less abundance that contribute to rumen digestion. These bacterial populations may or may not be variable within a herd or across dairies within a given geographic region. In this study, rumen fluid samples were collected from 81 Holsteins across four dairies from the state of Washington. DNA was extracted, amplified, and sequenced for bacterial 16S ribosomal RNA. Diversity indices were compared among the dairies using the Kruskal-Wallis test. Significance was declared at P ≤ 0.05. Results showed that bacterial communities were similar in rumen fluid from cattle within a dairy; however, there were significant differences in Shannon’s and Simpson’s diversity indices as well as Shannon’s and Simpson’s evenness indices among dairies. Across all cows from all farms, Prevotella was the predominant genus present with an average relative abundance of 65%.  Hallella (5%), Treponema (4%), Paraprevotella (3%), Anaeroplasma (3%), and Fibrobacter (2%) were also present in the ruminal bacterial communities. Results suggest that cattle at different dairies even within the same geographical region harbor different bacterial communities.  1Dehority, Burk A. (2003). Rumen Microbiology. Nottingham:  Nottingham University Press.